Marine Weather Net

Straits of Florida from west end of Seven Mile Bridge to south of Halfmoon Shoal out 20 to 60 NM Marine Forecast


TONIGHT

E
WINDS
5 - 10
KNOTS

SUNDAY

ESE
WINDS
5 - 10
KNOTS

SUNDAY NIGHT

ESE
WINDS
5 - 10
KNOTS

MONDAY

S
WINDS
5 - 10
KNOTS

The Marine Weather Forecast In Detail:
GMZ074 Forecast Issued: 426 PM EDT Sat Oct 23 2021

Tonight...East Winds 5 To 10 Knots. Seas 1 To 2 Feet. Scattered Showers And Isolated Thunderstorms.
Sunday...East To Southeast Winds 5 To 10 Knots. Seas Around 1 Foot. Scattered Showers And Isolated Thunderstorms.
Sunday Night...East To Southeast Winds 5 To 10 Knots, Becoming Southeast To South. Seas Around 1 Foot. Scattered Showers And Isolated Thunderstorms.
Monday...South Winds 5 To 10 Knots, Becoming Southwest To West In The Afternoon. Seas Around 1 Foot. Scattered Showers And Isolated Thunderstorms.
Monday Night...Northwest Winds 5 To 10 Knots. Seas Around 1 Foot. Scattered Showers.
Tuesday...West To Northwest Winds 5 To 10 Knots. Seas Around 1 Foot. Isolated Showers.
Tuesday Night...West To Northwest Winds 5 To 10 Knots. Seas Around 1 Foot. Isolated Showers.
Wednesday...Southwest To West Winds 5 To 10 Knots, Becoming South To Southwest In The Afternoon. Seas Around 1 Foot. Isolated Showers.
Wednesday Night...South Winds 5 To 10 Knots, Becoming South To Southwest And Increasing To Near 15 Knots. Seas Building To 3 To 5 Feet. Scattered Showers.
Thursday...South To Southwest Winds 15 To 20 Knots. Seas 4 To 5 Feet. Scattered Showers And Isolated Thunderstorms.
Thursday Night...Southwest Winds 15 To 20 Knots. Seas 4 To 6 Feet. Scattered Showers And Thunderstorms.
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Synopsis for Keys coastal waters from Ocean Reef to Dry Tortugas: GMZ005
426 PM EDT Sat Oct 23 2021

A weak, broad dome of high pressure will remain entrenched across the Atlantic, with the associated ridge axis extending across Central Florida. Light to gentle breezes are expected through Monday and drier conditions are anticipated Tuesday and Wednesday. A frontal boundary will approach Florida as early as Thursday, resulting in a period of elevated rain and thunder chances, and freshening southwesterly breezes.

Gulf Stream
The Approximate Shoreward Edge of the Gulf Stream as of October 22...
- 20 NM South of Dry Tortugas Light...on Loggerhead Key.
- 26 NM South of Cosgrove Shoal Light...off the Marquesas Keys.
- 29 NM South of Sand Key Light...off Key West.
- 28 NM South of Looe Key...off Big Pine Key.
- 32 NM South of Sombrero Key Light...off Marathon.
- 29 NM Southeast of Alligator Reef Light...off Islamorada.
- 19 NM Southeast of Molasses Reef Light...off Key Largo.
- 8 NM East of Carysfort Reef Light...off Ocean Reef.
Area Forecast Discussion
National Weather Service Key West FL
300pm EDT Sat Oct 23 2021

Unfortunately the day did not pan out quite as we were thinking. A cloud line is attempting to develop and managed to produce a lone shower. This shower briefly developed between Boca Chica and Stock Island and lasted about 15 to 30 minutes before dissipating. Sadly is appears that there was not enough filtered sunshine to really destabilize the lowest levels. This has resulted in almost no additional showers developing. BYX radar shows isolated showers remain present across the far eastern waters. These are due to an area of weak cyclonic circulation in association with a a weak inverted trough present in the same general area. These showers for most part have stay offshore. Meanwhile, convection is firing at the usual time across the southern mainland and have thus far remained there.

A low and mid level ridge is situated across central Florida and the eastern Gulf of Mexico. As a result low level winds are mainly from the northeast. This may allow for some of the convection to drift off the mainland and over the Florida Bay and adjacent Gulf waters. However, the flow is fairly weak and the convection may fall apart prior to this occurring. Otherwise, turning our attention back to the previously mentioned inverted trough, this feature will maintain a slow northwest trajectory.

This feature has been slowly increasing our moisture throughout the atmospheric column. In fact, this mornings 12Z RAOB (Radiosonde Observation or Upper-Air Observation) sounding should a PWAT (Precipitable Water) of 2 inches on the dot. Despite this addition in moisture, we lack any concrete forcing mechanisms. As such showers are developing mostly on mesoscale processes, but in the absence of any additional forcings, fall flat quickly.

With that said, we remain on the northern periphery of a mid level ridge located over the western Caribbean. Multiple shortwaves have been rounding this feature and moving across our area. One such shortwave looks to move over the area tonight and could be just enough uumph to get some showers and isolated thunderstorms going.

Otherwise, the inverted trough will move north of the area by Sunday and away from the Florida Keys. In its place, a vigorous shortwave will round the base of a longwave trough currently over the Intermountain West, and move across the area Monday. This will be our last best chance for rain until the end of the week. Then eyes turn to our first true cold front of the season. That being said, models differ drastically on the evolution of the parent low and associated cold front. Do not want to get into the weeds just yet. What we can say right now is that these differences will determine not only timing but whether or not we get hit with a one-two punch with multiple fronts. Either way, enhanced rain chances look to return as early as Thursday and could linger as late as Friday evening. The upcoming Halloween weekend however, looks to be dry at this time.

Marine
Light to gentle northeast breezes prevail across the Florida Keys coastal waters this afternoon and will continue.nue into this evening. Breezes will gradually clock around to the east and southeast by Sunday and further clock around towards the southwest Monday. A decaying front will push through Monday night with winds briefly becoming northwest. Ridging returns Tuesday with winds becoming southerly and gradually freshening ahead of a potential front on Thursday.

Climate
In 2005, a violent waterspout passed just west of Key West in the outermost rainband of approaching Hurricane Wilma at around 4 pm.

NOAA Key West FL Office: Watches - Warnings - Advisories
FL...None. GM...None.